Source Files, Continuations, and Comments

LunarBasic combines continued physical lines into logical source lines before parsing. Blank lines and comments are ignored so the parser can focus on real code.

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How Source Files Are Read

• Source is read one physical line at a time.
• Physical lines joined with _ are parsed as one logical source line.
• Blank lines and comments are ignored.
• Error messages include the file name, line number, and column number.

Whitespace

• Whitespace between tokens is ignored.
• Blank lines are ignored.

This means you can space code out for readability without changing how it is parsed.

Line Continuation

Place a standalone underscore at the end of a physical line to continue the statement on the next line. At least one whitespace character must appear immediately before the underscore.

total = firstValue + _
    secondValue + _
    thirdValue

DrawText font, _
    x, y, _
    "Hello"

• Only whitespace may follow the continuation underscore.
• Multiple consecutive lines can be continued.
• Indentation on continuation lines is optional.
• Continuation works in declarations, parameter and argument lists, grouped expressions, array dimensions and indexes, and control-flow conditions.
• Underscores inside identifiers, strings, or comments do not continue a line.
• A continuation underscore at the end of the file is a syntax error.

Function AddValues( _
    left As Integer, _
    right As Integer _
) As Integer
    Return ( _
        left + right _
    )
End Function

Apostrophe Comments

An apostrophe starts either a full-line comment or an inline comment.

Anything after the apostrophe on the same line is ignored.

Block Comments

Block comments start with Rem and end with End Rem.

• The match is case-insensitive.
• Leading and trailing whitespace are ignored when checking for Rem and End Rem.
• A line containing only Rem starts the block comment.
• A line containing only End Rem ends the block comment.
• Everything inside the block is ignored.
• If the file ends before End Rem appears, it is a syntax error.